<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        ul {
            margin: 0;
            padding: 0;
            list-style: none;
        }

        ul li {
            width: 100px;
            height: 200px;
            background: skyblue;
            text-align: center;
            line-height: 200px;
            font-size: 30px;
            float: right;
            margin: 10px;
        }
    </style>
</head>

<body>
    <!-- 浮动 -->
    <!-- 
        float:left /right/

     -->
    <ul>
        <li>1</li>
        <li>2</li>
        <li>3</li>
        <li>4</li>
    </ul>
    666
    <!-- 当元素浮动后，会脱离文档流 -->
    <!-- 只要浮动了元素，父级就会没有高 -->
</body>

</html>